Implantation is a complex process and involves various factors such as cytokines and hormones. Degradation and regeneration of the endometrial extra-cellular matrix (ECM) is a vital process that involves matrix metalloproteinases (MMPs). MMP, including MMP-2 (gelatinase A) and -9 (gelatinase B), play an important role in tissue remodeling in various physiological and pathological processes, such as implantation, ovarian and uterine functions during peri-partum, wound healing, cancer development etc. [
1,
2]. Although the roles of MMP during implantation are known for invasive placentation as occurs in humans and rodents [
3‐
9], knowledge concerning endometrium remodeling in non-invasive placentation, as occurs in ungulates, is limited. The important roles of MMP in endometrial remodeling, especially those of MMP-1 and -2, were reported in sheep [
10,
11]. Interstitial cells are responsible for their production, but epithelial cells are not present in the ovine endometrium [
10]. In goats, MMP-2 activity is regulated by co-localized membrane-type 1 MMP (MT1-MMP) and tissue inhibitor of metalloproteinase-2 (TIMP-2), and they control endometrium remodeling during gestation [
12]. In cattle, trophoblast cells attach to the surface of the epithelium on the caruncle, which is a specific region for implantation, and then the trophoblast cells and endometrial epithelia fuse and make binucleate or multinucleate cells on the caruncle [
3,
13,
14]. Although, the roles of MMP have been reported during peri-partum, termination of gestation, and post partum in cows [
2,
15], the detailed expression profiles of gelatinases have not been clarified during implantation; namely, the proteolysis mechanisms of the endometrial ECM are still obscure during implantation in cows. Many species of MMP and related molecules participate in this process, including TIMP and MT-MMP [
1]. During the implantation process, trophoblast cells eliminate epithelial cells, and the epithelium is reorganized [
13,
16]. Gelatinases may play a significant role in this process. After implantation, the newly formed binucleate and multinucleate cells produce many molecules, peptides, and hormones, such as placental lactogen, pregnancy-associated glycoproteins, prolactin-related proteins, steroid hormones, and heparanase [
3,
13,
17,
18]. Compared to invasive placentation, the mechanisms of this type of proteinase is unknown in cows, but it is just as important. Most embryo loss occurs during the early implantation period in cows. The cause of this usually relates to the uterine circumstances, which depend on humoral regulation and may depend on the spacio-temporal condition of the endometrium. Abnormalities in endometrial function cause early embryo loss in many species, and MMPs participate in the regulation of endometrial functions in ruminants [
11,
19,
20]. In the present study, MMP-2 and -9 mRNA were analyzed quantitatively using real-time PCR and microarray analysis, and the expression of their proteins was confirmed by gelatin zymography.